Recently, study on using a bone mineral density of a mandible to evaluate a skeletal bone mineral density of a whole body of a person has attracted attention. A non-patent literature 1 below reports that the bone mineral density of a dental alveolus of a mandible, or, more particularly, the bone mineral density at a location between premolars (or between the first and second premolars) and away by about 6 mm from the neck (the junction between the enamel and cementum portions) toward the apex is closely related to the skeletal bone mineral density of a person. It also shows experiments for evaluating the bone mineral density of an alveolus from a density of a radiograph of the alveolus, and, then, estimating the skeletal bone mineral density from the evaluation of the alveolar bone mineral density.    Non-Patent Literature 1: Grethe Jonasson, Gudrun Bankvall, Stavros Kiliaridis: Estimation of skeletal bone density by means of trabecular pattern of the alveolar bone, its interdental thickness, and the bone mass of the mandible; “ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY” September 2001, Volume 92, Number 3, p. 346-p.352.